Yi Yang,Shifeng Wen,Qingsong Wei,Wei Li,Jie Liu,Yusheng Shi
The TiAl/TiB 2 metal matrix composites (MMCs) are fabricated by selective laser melting (SLM), and the effects of scan line spacing on the grains feature, crystallographic texture, phases evolution mechanism and nanohardness have been systematic studied. With the increase of scan line spacing, relatively coarse grains with average grain size of 4.9 ± 0.2 μm and strong ( 0001 ) orientation gradually transforms into refined grains with average grain size of 4.2 ± 0.1 μm and dominated ( 11 2 ¯ 1 ) and ( 01 1 ¯ 1 ) orientations during the SLM process. The SLM-processed TiAl/TiB 2 MMCs samples are dominated by high-angle grain boundaries (HAGBs) and α 2 phase, with the increase of scan line spacing from 80 μm to 140 μm, both the volume fraction of HAGBs and α 2 phase decrease. During the SLM process, the phases evolution mechanism of TiAl/TiB 2 MMCs can be expressed as: (200)β first transformed to (11 2 ¯ 0)α 2 , (20 2 ¯ 0)α 2 and (110)γ, then the TiB 2 , residual B 2 and incompletely transformed γ phases randomly distribute in the α 2 matrix, and the orientation relationship of the α 2 , γ, B 2 and TiB 2 phases can be concluded as: ( 11 2 ¯ 0 ) α 2 // ( 110 ) B 2 // ( 110 ) γ// ( 110 ) TiB 2 . Besides, there are some TiB phase in the TiAl/TiB 2 MMCs which is induced by the Ti + TiB 2 → 2TiB reaction during SLM. The TiAl/TiB 2 MMCs samples show an ultra-high nanohardness ranging from 8.6 ± 0.4 GPa to 9.4 ± 0.5 GPa with the increase of scan line spacing, which is superior than that of the TiB 2 reinforced TiAl alloy counterpart (6.7 ± 0.4 GPa) fabricated by traditional roll bonding.
Yu Long,Tao Wang,Yan Wang,Xiaolong Huang,Yu Lei,Jianguan Hua,Biwei Deng,Yan Li
Two-photon polymerization (TPP) is one of the emerging technologies for manufacturing high-precision micro-nano 3D structures. Common resin materials used in TPP are limited to, for example, acrylates or epoxy oligomers. The mechanical properties of these resins are difficult to tune after exposure, limiting their applications in advanced fields such as biomedicine, soft robotics, and microelectronics. In this work, an elastomer photoresist based on polyurethane acrylate (PUA) is designed, which combines the flexibility of polyurethane with the rapid curing characteristics of acrylates. Microstructures with good self-supporting properties are prepared by TPP-3D printing, and the mechanical properties of the elastomer photoresist are tuned by controlling the line spacing and rotation angle. Through in-situ compression tests, it is found that the modulus of the elastomer photoresist could be tuned from 284 MPa to 665 MPa, the yield strength from 43 MPa to 59 MPa, and the initial cycle energy absorption from 18 MJ/m 3 to 27 MJ/m 3 , showcasing an effective strategy of tuning mechanical properties through printing parameters. Finally, three types of recoverable structures are designed and printed, validating the potential of this elastomer photoresist for applications in flexible electronics and microelectronic device protection. This study provides an effective approach for the design of elastomer photoresist and the tunable mechanical properties of TPP-3D printed structure.
危险品化学品经营许可证（带存储）